• Ocean and Polar Research
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• v.28 no.2
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• pp.129-144
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• 2006

Small-scale effects of sand mining on macrobenthic communities have been reported previously. However, little information is available as to how dredging affects the macrobenthic community structure. The objective of this study was to determine the impacts of large-scale exhibition dredging on the macrobenthic community of Gyeonggi Bay, Korea, where sand mining has continued for 20 years. Prior to dredging, the macrobenthic species composition was similar to that of areas near the dredging site, with several common dominant species found before dredging. After dredging, the number of species, density, and diversity (H') in the experimental area (sites 0 and 1) decreased significantly, but no difference was observed at other sites. Multivariate analysis (multidimensional scaling) revealed significant differences in community structure before and after dredging. The amphipod Urothoe grimaldii japonica, which was the most dominant species at sites 0,1, and 2, decreased rapidly at sites 0 and 1 after dredging, but no difference was observed at site 2. In addition, the index of multivariate dispersion (IMD) and the relative IMD (r. IMD) were large at sites 0 and 1, suggesting that the effects of dredging were direct at site 0 and 1, but indirect at site 2. The macrobenthic communities at sites 3 and 4 were not affected by dredging, but they were affected by physical conditions and biological interactions. We suggest that benthic biotope indices such as the IMD and r.IMD may constitute a valid tool for assessing the effects of dredging on the macrobenthic community; long-term monitoring is required to verify this.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.5
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• pp.423-432
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• 2004

In coastal area of Inchon, dredging and the disposal of dredged material for sea-wall construction and reclamation have increased in recent years. These activities may impact the benthic environment and result in changes in benthic communities, but little information is available on the extent and direction of these changes. We investigated whether there have been changes in the dominant macrobenthic species and benthic community over the last decade, and explored the relationship between environmental variables and spatial patterns of macrobenthic community structure. We sampled macrobenthos and recorded environmental variables in the coastal habitats of Inchon in March and June 2004. In total, 212 macrobenthic species were recorded during this study, predominately crustaceans $(34{\%})$, mollusks $(32{\%})$ and polychaetes $(21{\%})$. The mean density of macrobenthos was $1,393\;ind./m^{2}$.The most abundant species was Amphioplus japonicus $(20.5{\%})$, followed by Heteromastus filiformis $(14.4{\%})$, Theora fragilis $(8.2{\%})$ and Ampharete sp. $(4.0{\%})$. Over the past decade the dominant macrobenthic species in this area shifted. Multivariate analysis (multidimensional scaling) revealed significant differences in community structure among three regions: the middle part of the sampling area (B), site 8 (C) and other sites (A). Mean density varied significantly among the three regions, but no differences in the number of species and diversity (H') were observed. The distribution of the macrobenthic community was affected by environmental variables such as percentage sand content and sediment kurtosis. Species that were important in different areas included A. japonicus in region A, Raeta puchella in region B and T. fragilis in region C. The important species in regions B and C were filter-feeding bivalves, and the abundance of these species may be related to the increase in percentage sand content. We suggest that the sediment composition (percentage sand content) may be an important factor in determining the dominant species and structure of the macrobenthic communities in coastal Inchon. Long-term monitoring programs are necessary to understand ongoing changes in the benthic communities of this area.

• Journal of Soil and Groundwater Environment
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• v.13 no.5
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• pp.20-32
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• 2008

Runoff characteristics of the Oedocheon in Jeju island were investigated using the long-term stream stage monitoring data. At the Cheonah valley in the upstream area and Oedocheon downstream, annual runoff occurred 21 and 12 times, respectively, and their average runoff periods were 21 days and 12 days, respectively. Stream stage response time to rainfall was 4 hours, and storm-water transfer from the upstream, Cheonah valley, to the Oedocheon downstream took about 2 hours. The stream discharge measurements had been carried out from Feb. 2004 to Jul. 2005, and showed that normal discharge of the Oedocheon was 0.39 $m^3$/sec in average. Stage-discharge curves were developed to estimate base flow (normal discharge) and (direct) surface runoff. The base flow separations by a numerical filtering technique illustrated that annual surface runoff and base flow accounted respectively for 31.8${\sim}$36.5%, 63.5${\sim}$68.2% of the total stream discharge.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.2
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• pp.242-251
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• 2010

In comparison with other terrestrial ecosystems, rice paddies are unique because they provide the primary food source for over 50% of the world's population, and act as major sources of global methane. The present paper summerizes a long-term field study that combine carbon isotopes, and canopy-scale flux measurements in an irrigated rice paddy, in conjugation with continuous monitoring of environmental, and vegetational factors. Both $CO_2$, and methane fluxes were largely influenced by soil temperature, and moisture conditions, especially across drainage events. Soil-entrapped $CO_2$, and methane showed a gradually increasing trend throughout growing season, but rapidly decreased upon flood water drainage. These variations in flux were well correlated with changes in concentration, and isotope ratio of soil $CO_2$, and methane, and of atmospheric $CO_2$, and methane within, and above the canopy. The isotopic signature of the gas exchange process varied markedly in response to change in contribution of soil respiration, belowground storage, fraction of $CO_2$ recycled, magnitude, and direction of $CO_2$ exchange, transport mechanism, and fraction of methane oxidized. Our results clearly demonstrate that stable isotope analysis can be a useful tool to study underlying mechanisms of gas exchange processes under natural conditions.

• Microbiology and Biotechnology Letters
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• v.28 no.2
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• pp.117-123
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• 2000

The object of this work is to improve the maintenance of bioluminescence from stored Photobacterium phosphoreum in a view of developing continuous monitoring system for pollutants. The long-term experiments were performed to determine the effect of storage temperature and immobilization on the maintenance of bioluminescence and viability of P. phosphoreum. A naturally luminescent bacterium, P. phosphoreum was starved in 2.5% Nael solution at $20^{\circ}C$, $4^{\circ}C$, -$20^{\circ}C$ and -$70^{\circ}C$ for 30 days. In vivo luminescence was measured by luminometry, and total cell concentrations and concentrations of culturable and viable cells were determined by acridine orange staining, dilution plate counting, and direct viable counting, respectively. The bioluminescence emission from cells stored at 4De was maintained up to 10 days while those with starved cells at other temperature ranges decreased to background level within 3 days. In terms of viability of cells, concentrations of cells stored at $20^{\circ}C$ were rapidly decreased as a result of cell lysis, leading to a drop in culturable and viable counts while cells stored at $4^{\circ}C$ was shown viable but nonculturable state during starvation. With immobilized cells on strontium alginate, the bioluminescence showed higher maintenance than free cells and decreased with count number of nonculturable cells.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.8
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• pp.572-577
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• 2011

The unit load has simply been used to estimate total pollutant loading from non-point sources, however, it does not count on the variable pollutant loading according to land use characteristics and rainfall intensity. Since pollutant emission from the watershed is strongly dependent on the rainfall intensity, it is necessary to find out the relationship between pollutant loading and rainfall intensity. The objective of this study is to develop simple and easy method to compute non-point source pollution loads with consideration of rainfall intensity. Two non-point source removal facility at Gyeongan-dong (Gwangju-si) and Mohyeon-myeon (Yongin-si), Gyeonggi-do was selected to monitor total rainfall, rainfall intensity, runoff characteristics and water quality from June to November, 2010. Most of Event Mean Concentrations (EMC) of measured water quality data were higher in Gyeongan which has urban land use than in Mohyeon which has rural land use. For the case of TP (Total Phosphorus), Mohyeon has higher values by the influence of larger chemical uses such as fertilizer. The relationship between non-point source pollution load and rainfall intensity is perfectly well explained by cubic regression with 0.33~0.81 coefficients of determination($R^2$). It is expected that the pollution loading function based on the long-term monitoring would be very useful with good accuracy in computing non-point source pollution load, where a rainfall intensity is highly variable.

• Journal of Conservation Science
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• v.32 no.3
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• pp.395-402
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• 2016

The impact of a large water control project on surrounding environment(temperature and relative humidity, precipitation, wind speed, present weather and visibility) was monitored. The survey have targeted on Silleuksa temple which is located in the waterside. The number of foggy days emerged as an environmental factor that can cause damage to cultural heritage. Under construction of weir since 2011, monthly relative humidity of Yeoju and Icheon was dropped to 9.6%. It depends on decrease in the number of raining days and precipitation of each year. Silleuksa temple is contiguous to Namhan River and only 100 m away from the waterside. Average wind speed is 0.5 m/s. Silleuksa has a site environmental factors which is often foggy. The number of foggy days of Silleuksa temple declined to 53 days soon after weir's completion. In case of fog, relative humidity of outside was higher than that of outside and inside of Josadang Shrine. Relative humidity difference of outside and inside of Josadang Shrine was 5.4% on average. Relative humidity of the number of foggy days is 6.3% higher on average than that of fine days. The width and dimensions of Namhan River increased by 1.45 times after weir's construction. It can change the number of foggy days. A long-term monitoring is positively necessary on fog occurrence and relative humidity.

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.4
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• pp.297-309
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• 2016

This study was carried out to investigate the differences in sedimentary environments and benthic polychaete communities between farming grounds and natural habitats (non-farming ground) in Gamak Bay. Sampling stations of natural habitats were evenly distributed in the entire bay. And mussel farm, oyster farm and ark-shell farm were selected as farming grounds. Dominant sedimentary facies was mud in most sampling stations of farming grounds and natural habitats. However organic contents were higher in the farming grounds than natural habitats of the bay. The species number and mean density of polychaetous community in the natural habitats were greater than those from the farming grounds. Lumbrineris longifolia, known as potential organic enrichment indicator species, was first dominant species both in farming grounds and natural habitats of the bay. However, the next dominant species consisted of different species between two benthic habitats. As a result of community analysis using cluster analysis and nMDS, the natural habitats were divided into several station groups, but most of stations in farming grounds were clustered into one group. Pearson' correlation analysis and PCA showed high relationships between sedimentary environmental factors and benthic polychaetous community in natural habitats, but low or no relationships in farming grounds. That means benthic polychaetous community established in farming ground was under unusual condition such as high input of organic matter. Thus it is necessary to improve the benthic environmental quality of the farming grounds as well as the north-western inner part in Gamak Bay through long-term monitoring efforts.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.5
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• pp.527-534
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• 2011

This paper describes an analysis of topographical changes to the Eulsuk-Island at the Nakdong River Estuary using a long-term dataset of high resolution aerial images from 1983 to 2007. Ground control surveying was performed at some feature points using GPS(Global Positioning System) to accomplish AT(Aerial Triangulation) for past aerial images. Even if some still existing feature points appeared on old aerial images were used as GCPs(Ground Control Points) for past aerial images in AT, its accuracy reached at 1m level. Since then, a quantitative analysis of topographical changes was conducted on digital orthophotos produced by a series of aerial images taken by different years. The change volume of total area, construction, vegetation, buildings and roads could be extracted per each period in study area. The total area decreased from 1983 to 1992, but it has not almost changed since 1992. According to the continuous development, the area of vegetation has steadily decreased, while that of buildings and roads has generally increased. The result of this study can provide us with invaluable base data for further topographical change monitoring in Eulsuk-Island and Nakdong River estuary caused by continuous development in this area.

• Journal of the Korean Society of Marine Environment & Safety
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• v.10 no.2 s.21
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• pp.81-88
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• 2004

We review the adaptation strategies of the 21st climate change in an application to sea level rise. For the development of appropriate adaptation strategies on the coast vulnerable to the sea level rise, we have to consider the issues such as where to adapt, how to adapt, and when to adapt. The coastal target needed adaptation can be found by the evaluation of adaptive capacity of the coastal zone which requires the understanding of impacts and adaptive potential of the natural and socioeconomic systems in the coastal zone. Planned adaptation options to sea level rise can be classified into three generic approaches as managed retreat, accommodation, and protection In practice, the implementation of the options requires the analysis of land use, degree of vulnerability, cost and benefit, etc, and may be combination of the options rather than one approach. In terms of the response timing, the adaptation can be grouped as anticipatory and reactive ones. Generally it is more effective to consider both anticipatory and reactive adaptations at the same time for the impacts of future sea level rise. Due to the scientific uncertainty of climate change issues including sea level rise, the adaptation processes have to be designed to deal with a series of processes such as information md awareness establishment, planning and design implementation, and monitoring and evaluation in continuity and long-term period.